Embodiments of the present invention relate generally to apparatus and methods used for supplying power. More particularly, embodiments of the present invention relate to supplying power using switching circuitry with charge, voltage, and/or current sensing.
A familiar problem in system engineering is the subsystem having power requirements which are not met by the main supply. In such cases, the available supply rails are not directly usable. Battery voltage, when available, may also not be an option, due to a lack of space, safety concerns, reliability concerns, etc. Thus, voltage converters are often used to generate the desired voltage levels, and, as is well known to those skilled in the art, charge pumps are often the best choice when some combination of low power, simplicity, and low cost are required.
Charge-pump voltage converters usually make use of ceramic or electrolytic capacitors to store and transfer energy. Capacitive voltage conversion is achieved by periodically switching a capacitor. Passive diodes may perform this switching function in the simplest cases, provided an alternating voltage source is available. Otherwise, DC input voltage levels require the use of active switches which first charge a capacitor by connecting it across a voltage source. Later, the switches are used to connect the capacitor to the output or load in a way that produces a different voltage level.
Thus, most commonly available charge pump power supplies and DC-to-DC converters use switched capacitors for energy conversion, in conjunction with rectifiers, transistors, and/or integrated circuits. However, most DCxe2x80x94DC generators using external capacitors are sensitive to capacitance mismatch. Further, most regulators use an external clock or oscillator which switches capacitors in and out of the circuit whether or not the load demands it. Therefore, there is a need in the art for a regulator design which does not use a load-insensitive oscillator or clock to direct power transfer. Such a design might operate to reduce the amount of circuitry required to transfer power to a load, and eliminate unnecessary state changes, contributing to an increase in efficiency and/or a decrease in power consumption. There is also a need in the art for a regulator design which tolerates capacitor mismatch, further reducing manufacturing expense by allowing the purchase of capacitors with wider tolerance variations.